1. Field of the Invention
This invention relates to a method of depositing a metal on a surface and more particularly, to a method of selectively depositing a metal on a surface of an electrically non-conducting substrate.
2. Discussion of the Prior Art
There is a growing need in various devices and circuit applications for an inexpensive process which will produce adherent conducting circuit patterns on a non-conductor surface. Most of the processes used for metallic pattern generation involve a photographic step. Pattern resolution may be good but most methods are often slow, involving many process steps, and are relatively expensive.
A conventional method for producing macro circuit pattern employs a copper-clad insulator board coated with a photoresist material which is photoexposed and chemically processed to selectively remove copper, leaving a desired circuit pattern. This method is effective but wasteful of copper and chemicals. The high cost of this method has encouraged research and development toward new techniques for metallic pattern generation on a non-conductor surface.
An electroless metal-deposition process is especially attractive for metallic pattern generation since one only needs to produce a pattern of a suitable catalyst on a substrate and metal deposition will occur only on that pattern. However, conventional electroless metal techniques usually involve separate sensitizing and activating steps which are followed by a photoresist masking step prior to immersion in an electroless deposition solution. This plurality of step and the sequency required thereof is time consuming and expensive. Also, where a substrate has a through-hole, additional electroless deposition conditioning steps are often required and add to the expense of manufacture.
A method for selective metal deposition which eliminates one or more conventional steps is therefore desired and needed.